TWO GIG-ANTIC TYPES OF ARENACEOUS FORAMINIFERA. 
723 
singular conformity to that which was contemporaneously set forth in more detail in my 
Systematic Treatise. — This striking coincidence between the results of the studies inde- 
pendently pursued by Professor Beuss and ourselves, has tended, I have good reason for 
believing, to procure for them a general reception among Continental as well as British 
Zoologists, which they might otherwise have been long in gaining. 
The Arenaceous group, thus definitely constituted, was considered by Messrs. Parker 
and T. Rupert Jones as consisting only of one Family, the Lituolida ; under which they 
ranked the three Genera Trochammina, Lituola, and Valvulina, each of them possessing 
such a wide range of morphological variation, as to present in their aggregate a most 
curious series of imitations or ‘isomorphs’ of true shelly Foraminifera, Vitreous as well 
as Porcellanous. “It is not improbable,” I remarked (§ 205), “that future research 
may add largely to our knowledge of these Arenaceous forms;” and this anticipation 
has been remarkably confirmed by the results of subsequent investigations. For whilst 
a singular variety of recent Arenaceous Foraminifera, some of them of large dimensions, 
have been brought up by the Dredging operations which have been lately carried down 
to great depths in the Sea, it has been discovered that certain problematical fossils of 
very regular globose form, sometimes attaining 2 inches in diameter, occurring in the 
Upper Greensand near Cambridge and in the Isle of Wight, and formerly supposed to 
be Sponges, are in reality gigantic Arenaceous Foraminifera ; and the like character has 
been recognized in a series of fossils which were some time since brought from Persia 
by the late Mr. Loftus, the striking resemblance of which, both in form and general 
characters, to Alveolina, seemed to justify their assignment to the Foraminiferal type, 
notwithstanding that their enormous dimensions seemed almost to forbid such a deter- 
mination. 
Being aware that my friend Mr. H. B. Brady had made a special study of these 
gigantic Alveoline fossils, and had come to the conclusion that they constitute a new and 
peculiar type of Arenaceous Foraminifera, to which he has given the generic designation 
Loftusia, I thought it likely that he might be able still further to elucidate their structure 
by a knowledge of the results I had obtained from the examination of the non-infiltrated 
specimens of Parkeria, which I accordingly communicated to him. My anticipations 
were so abundantly justified by the results of Mr. Brady’s re-examination of the minute 
structure of Loftusia under the new light thus reflected on it (so to speak) from Parkeria , 
that I at once perceived that it would be to our mutual advantage that the descriptions 
of these two extraordinary types should be associated in one Memoir ; and on proposing 
this to Mr. Brady, I immediately obtained his cordial acquiescence. For the descrip- 
tion of Parkeria, therefore, I hold myself responsible, as Mr. Brady does for that of 
Loftusia ; but each of us has verified all the more important parts of the description 
given by the other. 
It will be found that both these organisms depart so widely in general plan of struc- 
ture from any Foraminiferal type previously known, that they must for the present be 
ranked entirely by themselves. If only infiltrated specimens of the Cambridge fossil 
5 d 2 
